tests: link to gtest source files directly
tests: link to gtest source files directly

Upstream gtest does not provide a libgtest.a anymore to link against.
Instead, they want you to compile it from source all the time when you
use them with your own projects.

Adapt the test makefile to use the gtest source in the NaCl SDK, and
have it build gtest-all.cc directly instead of using libgtest.a.

Change-Id: I0aa087c35d32a6446402a5d33f487c6877471c84

vapier/chrome-ext-wicked-good-unarchiver,vapier/chrome-ext-wicked-good-unarchiver,vapier/chrome-ext-wicked-good-unarchiver,vapier/chrome-ext-wicked-good-unarchiver,vapier/chrome-ext-wicked-good-unarchiver